Genome Rearrangement Models

Random Breakage Model

Genome rearrangement may occur randomly, i.e. if a rearrangement does occur, then the location at which it occurs could be uniformly distributed throughout the genome.

Under this model, the distribution of synteny block size should follow an exponential distribution, since they are being broken apart at a constant, random rate. In fact, human and mice synteny blocks.

However, evolutionary pressure argues against the random breakage model. An organism will die if critical genes are moved to the wrong location, but genetic death is not that common.

Fragile Breakage Model

The number of breakpoints in the human-mouse mostly come from “fragile” regions, that are randomly distributed in the genome. Long, stable regions of the genome are relatively unaffected by rearrangement.